Anti-inflammatory drugs like aspirin may reduce breast cancer by up to 20 per cent, according to an extensive review carried out by experts at London's Guy's Hospital and published in the March issue of IJCP, the International Journal of Clinical Practice.
But they stress that further research is needed to determine the best type, dose and duration and whether the benefits of regularly using non-steroidal anti-inflammatory drugs (NSAIDs) outweigh the side effects, especially for high-risk groups.
"Our review of research published over the last 27 years suggests that, in addition to possible prevention, there may also be a role for NSAIDs in the treatment of women with established breast cancer" says Professor Ian Fentiman from the Hedley Atkins Breast Unit at the hospital, part of Guy's and St Thomas' NHS Foundation Trust.
"NSAID use could be combined with hormone therapy or used to relieve symptoms in the commonest cause of cancer-related deaths in women."
Professor Fentiman and Mr Avi Agrawal reviewed 21 studies covering more than 37,000 women published between 1980 and 2007.
Their review included 11 studies of women with breast cancer and ten studies that compared women who did and did not have the disease.
"The purpose of a review like this is to look at a wide range of published studies and see if it is possible to pull together all the findings and come to any overarching conclusions" explains Professor Fentiman. "This includes looking at any conflicting results and exploring how the studies were carried out.
"For example some of the studies we looked at as part of this review found no links between NSAIDs and reduced levels of breast cancer, while others suggested that taking NSAIDs can reduce the breast cancer risk by about a fifth.
"Having weighed up the findings from over 20 studies, we have concluded that NSAIDs may well offer significant protection against developing breast cancer in the first place and may provide a useful addition to the treatment currently available to women who already have the disease.
"Recent studies of NSAIDs use have shown about a 20 per cent risk reduction in the incidence of breast cancer, but this benefit may be confined to aspirin use alone and not other NSAIDs."
Previous studies have suggested that NSAIDs like aspirin and ibuprofen, which have traditionally been used as mainstream non-prescription analgesics, may provide protection against coronary heart disease and some malignancies, such as colorectal cancer.
But Professor Fentiman is urging caution until further research fully weighs up the pros and cons of using NSAIDs to prevent and treat breast cancer.
"Our review did not look at the potential side effects of using NSAIDs on a regular basis" stresses Professor Fentiman "These can include gastrointestinal bleeding and perforation which can carry a significant risk of ill health and death.
"It would be essential to take these negative effects into account before we could justify routinely using NSAIDs like aspirin to prevent breast cancer.
"More research is clearly needed and we are not advocating that women take these non prescription drugs routinely until the benefits and risks are clearer.
"But our findings clearly indicate that these popular over-the-counter drugs could, if used correctly, play an important role in preventing and treating breast cancer."
Notes to editors
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